PROJECT SUMMARY The goal of this administrative supplement is to acquire an advanced optical tweezers instrument. Capitalizing on the progress made in the previous two years of funding, this instrument will be used to conduct experiments to probe key questions within the scope of the parent grant. These questions include intermediates along binding pathways of intrinsically disordered proteins, conformational dynamics of disordered proteins under macromolecular crowding, and physical properties of protein droplets formed by liquid-liquid phase separation. The instruments complements well the ongoing efforts of the parent grant and will significantly raise the quality and impact of the research.